Hi Alper Tonga,
I doubt you can rename the output, however once you get the output then you can rename the file.
Thanks Rohit ... I think that it would be nice to be able to apply a naming preset for a newly created HDR file in Lr ... like any other newly created file in an another application..
Reasons NOT to rename-
The HDR derivative adds the suffix -HDR automatically.
HDRs are easily searchable. Test search > Filename / Contains / hdr.
The HDR sits besides the originals in Library grid when file sort is by Filename.
Also easier to Group into a Stack with the HDR on top and originals below.
Adding a Keyword "HDR" can easily find also.